How to handle connection loss uploading to Firebase iOS? - swift

Question

I have a frontend Swift application in which users are to upload large videos and photos to Firebase Storage. I am currently working on error handling. The documentation does a good job of explaining error handling from Google's sever side of things, however it does not cover how to deal with connection loss.
This is the error handling directly from the documentation:
...
// Upload file and metadata to the object 'images/mountains.jpg'
let uploadTask = storageRef.putFile(from: localFile, metadata: metadata)
uploadTask.observe(.failure) { snapshot in
if let error = snapshot.error as? NSError {
switch (StorageErrorCode(rawValue: error.code)!) {
case .objectNotFound:
// File doesn't exist
break
case .unauthorized:
// User doesn't have permission to access file
break
case .cancelled:
// User canceled the upload
break
/* ... */
case .unknown:
// Unknown error occurred, inspect the server response
break
default:
// A separate error occurred. This is a good place to retry the upload.
break
}
}
}
I have done some tests on my device where the upload begins with no network connection. The following gets automatically printed to the console every second or so after the network goes down:
2020-07-06 01:38:28.361559-0700 Rage[12281:1978025] Connection 9: failed to connect 1:50, reason -1
2020-07-06 01:38:28.361648-0700 Rage[12281:1978025] Connection 9: encountered error(1:50)
2020-07-06 01:38:28.366906-0700 Rage[12281:1978025] Task <320E9387-F725-4AEA-B3BE-76425F73F9F7>.<6> HTTP load failed, 0/0 bytes (error code: -1009 [1:50])
2020-07-06 01:38:28.368381-0700 Rage[12281:1978042] Task <320E9387-F725-4AEA-B3BE-76425F73F9F7>.<6> finished with error [-1009] Error Domain=NSURLErrorDomain Code=-1009 "The Internet connection appears to be offline." UserInfo={_kCFStreamErrorCodeKey=50, NSUnderlyingError=0x280a581e0 {Error Domain=kCFErrorDomainCFNetwork Code=-1009 "(null)" UserInfo={_kCFStreamErrorCodeKey=50, _kCFStreamErrorDomainKey=1}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <320E9387-F725-4AEA-B3BE-76425F73F9F7>.<6>, _NSURLErrorRelatedURLSessionTaskErrorKey=(
"LocalDataTask <320E9387-F725-4AEA-B3BE-76425F73F9F7>.<6>"
), NSLocalizedDescription=The Internet connection appears to be offline., NSErrorFailingURLStringKey=https://firebasestorage.googleapis.com/v0/b/rage-5940.appspot.com/o/event%2FBEC3B24F-5F97-4B6A-8FD3-5DC2F7D37AFB.mp4?uploadType=resumable&name=event%2FBEC3B24F-5F97-4B6A-8FD3-5DC2F7D37AFB.mp4, NSErrorFailingURLKey=https://firebasestorage.googleapis.com/v0/b/rage-5940.appspot.com/o/event%2FBEC3B24F-5F97-4B6A-8FD3-5DC2F7D37AFB.mp4?uploadType=resumable&name=event%2FBEC3B24F-5F97-4B6A-8FD3-5DC2F7D37AFB.mp4, _kCFStreamErrorDomainKey=1}
Is this Firebase throwing these errors? If so they are probably being thrown trying to create a storageRef before the uploadTask could even begin, and thus escape any provided error handling.
Is there anyway to catch these network errors?

Answer 1

Did you try this?
if error._code == NSURLErrorNetworkConnectionLost {
}
there are a couple of more you can check with them:
NSURLErrorTimedOut
NSURLErrorNotConnectedToInternet
NSURLErrorCannotConnectToHost